PbS/CuS hetero-nanostructured (HNS) quantum dots were successfully prepared through cation exchange reaction. Additionally, it was possible to control the CuS amounts through a low temperature process. As the CuS is formed, the band edge absorption of PbS decreases, and a large absorption is obtained in the NIR region due to the surface plasmon effect (SPR), which is a result of CuS vacancy. PbS/CuS HNS quantum dots with these unique optical properties and structures were applied to solar cells. Cell characteristics are improved by the ease of hole transport, which can be explained from the p-type property of CuS. Optimization of cell characteristics was achieved by controlled CuS concentrations and PCE of 9.32% was obtained. The reason for the optimal CuS concentration was explained by the transient PL decays measurement on TiO2 and Al2O3 substrates.
